Face mask for a helmet



FIG. 1 is a front elevation view of a face mask for a helmet showing my new design;

FIG. 2 is a rear elevation view thereof; and,

FIG. 3 is a side perspective view thereof.

The broken lines shown in FIGS. 1-3 are for illustrative purposes only and form no part of the claimed design. 

I claim the ornamental design for a face mask for a helmet, as shown and described. 